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How To Do Multi-level Steel Structure

Jan 11, 2018

The industrial buildings with a total height of less than 24m and a total height of less than 24m are defined as multi-storey steel structures;The above height is defined as a high-rise steel structure.Among them, the number and height of civil buildings are in harmony with China's building fire prevention codes, and the industrial buildings are generally high in height and are determined according to actual engineering experience.

Light frame and light frame - support steel structure is suitable for multi-storey civil buildings and floor equivalent live load less than 8KN/m2 and construction height is less than 20m.

In the unit of structural system, the form of the framework is clear, the form of support, shear wall and cylinder is rich, and the common form is listed in the classification table of structural system.Support of energy dissipation is commonly used in center - support structure in the framework of support, can also be used to form a tube or tube structure of ordinary truss oblique grid shell, in the eccentric support structure with energy dissipation function of the beam end overlap, is generally not used at the same time;The diagonal grid tube is made of all cross - diagonal rods, which can provide great rigidity, and has been applied in the structure of guangzhou TV tower and guangzhou sita.The existing examples of the shear wall cylinder in China are formed by the steel plate filling frame, which is used in tianjin jintower, which is over 300 meters.

The subdivision of the tube structure is based on the position relation between the tube and the frame or the tube.The tube and the tube are adjacent to the combination of the position of the beam;Shell and frame combination for frame drum, and can be further divided into lateral efficiency is highest in the traditional sense of peripheral for the inside of a cylinder, as the main vertical load under the framework of the outer barrel inner box structure, and the traditional reinforced concrete frame core tube structure similar to cylinder, surrounding is within the framework of the casing outside the cylinder structure, and multiple cylinder in the framework of free layout frame tube structure.

Due to the difference in force and deformation characteristics of different structural systems, there are also significant differences in ductility, and the ductility of multi-channel anti-lateral forces and the structural system with non-buckling mode is higher.At the same time, the ductility of the structure also depends on whether there is brittle failure in the node area and whether there is enough ductility in the plastic zone.

Listed in the classification system, framework - eccentric support structure, the energy dissipation brace of concentrically braced structures, the steel wall frame - shear wall structure, do not use skew the grid drum drum of cylinder and cone beam structure, generally for high ductility level structure types;The tubular structure of all cylinders is usually of low ductile grade structure.

With high ductility of the structure can withstand greater deformation in plastic stage and not a component buckling and overall collapse, thus has better energy dissipation capacity, if the fortification intensity should have an equal amount on the structure's capacity to absorb seismic energy as aseismic design criterion, the high ductility of structure should allow lower ductility structure earlier into the plastic.

Buckling constraint support can improve the ductility of structure, and to compare - eccentrically braced frame structure, its ductility enhancement is more controllable, so depending on the proportion of all support, concentrically braced structures for highest height can be increased by 20%.

The dual anti-lateral force system refers to the structure system with two lateral forces, and the second line has a horizontal bearing capacity not less than 25% of the total horizontal shear force.

Cantilever truss and surrounding truss can improve lateral contribution of surrounding framework, when both Settings, the effect is more apparent, commonly used in frame tube structure, can also be used to need to improve lateral peripheral component contribution of various kinds of structural system.The upper and lower chord of the boom truss must be pulled through the barrel body, while the body of the tube in the string can be set up enough to support the self-balance of the shaft force in the tube.Setting the number and position of the boom truss should not only consider its overall anti-lateral efficiency, but also take into account the bearing capacity of its connected components and nodes.

For super high - rise steel structure, wind load often plays a controlling role, and it is of great significance to select the shape of small wind pressure.Under certain conditions, the eddy current loss caused by the structure of the horizontal wind vibration effect is significant, the structure of the selection of flat, elevation Angle and processing will have obvious effect of horizontal wind vibration, should through the gas spring model wind tunnel test and numerical simulation of the wind direction sensitive structure of horizontal vibration effect were studied.

When the multi-layer steel structure is set up in the basement, the houses are generally higher, and the steel frame column should be extended to the basement level.The support of the vertical continuous arrangement in the frame - support structure is to avoid the formation stiffness mutation at the bottom of the seismic response, which is unfavorable to the earthquake, and the support needs to be extended to the basement.